Thanks for the additional information and answers to my questions.
I suspect you didn't insert the thermometer in quite far enough since this is a bit on the low side. Normal temps are 100-102.5 but at least we know it's probably not elevated.
When you pinch a dog's toes, they should retract or pull away since this is an involuntary reflex. The fact that he did so is a good thing.
It doesn't sound as if bruising or soreness would be the reason he can't support himself. Even if he did sustain some sort of soft tissue injury, I'd expect him to be walking although he might be quite stiff. Therefore, other possible explanations for his behavior include:
A problem with his spine where there's compression of his cord by either a disc or mass. It's certainly possible that his fall might have caused this problem although in many cases, there is no known event which can be identified. A thorough neurolgic exam is often enough to confirm this problem although sometimes spinal x-rays are suggested or additional testing such as an MRI is needed to confirm.
If this is the case, then the sooner Sparky is seen, the better. The longer the spinal cord is compressed, then the more severe the damage that might be done....which would be irreversible in some cases.
I'm not trying to alarm you but provide you with all of the information.
There are other possible causes such as Tick Paralysis or a condition called Discospondylitis which is an infection along the vertebrae but I'm not a huge fan of coincidence so these seem less likely to be the problem.
You're not going to be able to increase his Meloxidyl but you could possibly increase his Gabapentin dose if I know how much he weighs.
He might also need muscle relaxers which would have to be dispensed by a vet (which you probably already know).
If the fall had happened within or less than 24 hours ago, then I might advise giving him more time to see if he would come around but I'm a little concerned that so much time has passed and he's not willing to stand.
A vet visit might be prudent if at all possible but if you want to increase his Gabapentin dose, please let me now how much he weighs. Deb